The present invention relates generally to improvements in dust collectors and the like, and more particularly to an improved construction by which the container for receiving and containing the collected dust particles can be provided with an air-tight seal for improving the operation of the dust collector.
Briefly summarized, industrial dust collectors are provided with a housing in which a plurality of filter elements are disposed, usually cylindrical pleated paper filter elements. Air having particles of matter entrained therein is caused to flow through the filter elements, usually whereby the entrained particles in the air are deposited on the exposed surfaces of the filter elements. It is also common practice to provide such dust collectors with an arrangement for cleaning the filter elements at periodic intervals by causing a flow of air to pass through the filters in a reverse direction as compared with the normal air flow through the filter so that the particles collected thereon are blown off or otherwise separated from the filter and permitted to fall downwardly in the housing where the particles are received and stored in the dust collector until they can be removed at suitable intervals.
The most common way in which the collected dust particles are removed is to provide a drum or similar container that can be placed directly beneath the hopper, and provide the hopper with a selectively operable valve (e.g. a slide valve) that normally closes the hopper and blocks the flow of particles from the hopper to the drum, and that can be opened when needed to permit the particles collected in the hopper to flow into the drum, after which the valve is closed and the drum can be taken away to another location at which the particles can be properly disposed of, and a fresh, empty drum is placed under the hopper to receive the next load of collected particles.
During normal operation of this hopper, a vacuum is imposed across the filter elements to cause the above described flow of air therethrough, and it is important that there be no significant flow of air within the hopper portion of the dust collector because any such air flow tends to disturb the particles collected in the hopper to an extent that they may become reentrained in the air flow through the filter elements, all of which reduces the efficiency of the dust collector and the active life of the filter elements.
Because of this desired zero flow condition, it is important for the collecting drum, even though it was to be removable from the hopper as described above, to have a substantially air-tight seal with the drum so that air is not drawn into the hopper at its connection with the drum during normal operation of the dust collector, and there are several known methods of providing such a seal.
First, it is known to utilize a conventional rotary air-lock valve that includes a rotating valving member in a cylindrical valve housing. At one position of the valve member, the openings therein are aligned with the openings in the valve housing so that the dust particles can fall through the valve and into the drum. When the valve member is rotated a predetermined amount (e.g. 90 degrees), the aforesaid openings are no longer aligned, and the hopper is sealed. While such valves are generally satisfactory, they are relatively expensive, and the required seal elements between the valve member and the valve housing tend to wear out generally because of the construction of moving mechanical parts and the constant exposure of the seal elements to the abrasiveness of the collected particles. Similarly, a so-called double dump valve is also used to seal the hopper by providing a pair of pivoted valve plates that are arranged to permit flow from the hopper when both valve plates are opened simultaneously. Because these dump valves also have moving parts and exposed seal elements, they have the same disadvantages as the rotary valves and they are more inclined to leak.
Finally, a slide gate and drum arrangements is perhaps the most popular sealing valve used in dust collectors, probably because it is relatively inexpensive in comparison with the rotary air-lock valve and double dump valve. The slide valve is normally open during the time the dust collector is operating, and it is closed only when the drum becomes filled with dust and must be replaced with an empty drum. Because the slide valve is open during normal operation, it becomes particularly important that the removable lid for the drum must have a good, substantially air-tight seal with the container portion of the drum to prevent the flow of air into the hopper caused by the vacuum in the dust collector during operation. At the present time, the lid of the drum is sealed to the container portion of the drum only by providing a sealing material (e.g. neoprene) between the circular lip of the container portion and the flat bottom surface of the lid. Under new or ideal conditions, this seal is usually sufficient, but as a practical matter the drums and their lids are subject to rough treatment during the handling thereof, and such rough treatment ultimately results in the lids becoming bent, or the circular lip of the container portion becoming out of round or dented, or some other condition that will adversely affect the seal between the lip and the lid, all of which can affect the efficiency of the dust collector and the life expectancy of the filter elements as described above.
In accordance with the present invention, the aforesaid drawback of conventional sealing arrangements are overcome or significantly alleviated.